MUC5AC and colitis: Mucus layer thickness has been thought to reflect the function of the gut barrier and protect epithelia from harmful factors.19 Occludin is an important transmembrane and intracellular tight junction.5,20 Similarly, the mucin family is a critical component of the gut barrier.28 Alterations in tight junction protein expression and distribution have been considered key factors in the onset of colonic inflammation and UC.